In relational interpretation of quantum mechanics (RQM)  [1]}, [2]}, [3]}, [4]}, [5]}, measurement result is considered meaningful only relative to the system that interacts with the measured system. A definite measurement result is referred as a fact. Quantum theory is about conditional probability for facts, given other facts. [6]} introduces the concept of stable fact in the following sense. If, given the probability \(p(a_i)\)  for \(N\)  mutual exclusive facts \(a_i (i=1\ldots N)\)  and the conditional probability of another fact \(b\) , \(p(b|a_i)\) , the probability \(p(b)\)  (dropping index \(j\)  for \(b_j\) ) is given by (REF ), then facts \(a_i\)  are considered stable.
